This is a simple trick from Instructables user Jake22 for quickly making secure handcuffs from a length of paracord.
Back during my military service we used to use these for POW’s. Zip tie handcuffs are much more common now.
As with all restraints – the object is to restrict the movement of a supervised detainee.
It works like a prusik knot in that it is a friction hitch, it really clamps down on the loops and even without the follow up square knot the friction makes it very difficult to loosen the loops.